Localization of the Brain

Definition and Types of Localization

• Localization: Every behavior is linked to a specific brain region.
• Relative Localization: Each structure is associated with certain functions (e.g., Frontal lobe and impulse control).
• Strict Localization: Specific parts of the brain have specific functions (e.g., Amygdala and emotions).

Methods to Study Localization

1. Accidental Damage
2. Deliberate Damage/ Lesions
3. Brain Stimulation (Electrodes/ Brain scans)

Feinstein et al. (2011) - Case Study on Strict Localization

Aim

• Investigate the role of the human amygdala in experiencing and inducing fear.

Procedure

• Studied a rare patient (SM) with focal bilateral lesions.
• Provoked SM with snakes, spiders, haunted house tours, and horror films.
• Assessed SM’s fear reactions and self-reported fear levels using questionnaires and real-life sampling over three months.

Findings

• SM showed an absence of fear but experienced other basic emotions.
• Concluded that the amygdala plays a crucial role in triggering fear.

Conclusion

• The study supports the notion of strict lateralization, highlighting the amygdala's role in fear induction and experience.

Maguire et al. (2000) - Natural Experiment on Spatial Navigation

Aim

• Examine structural changes in brains of London taxi drivers with extensive spatial navigation experience.

Procedure

• Involved 16 right-handed male London taxi drivers and 50 right-handed male non-taxi drivers.
• Conducted structural MRI scans.
• Used voxel-based morphometry and pixel counting for gray matter measurement in the hippocampus.

Findings

• Increased gray matter in the right and left posterior hippocampi of taxi drivers.
• Established the role of the hippocampus in spatial navigation.

Evaluation

Reliability:

• Study was not repeated; potential for anomalous results.

Bias:

• Researcher Bias reduced through single-blind design.

Sampling:

• Limited to male London taxi drivers; lacks broader representativeness.

Methodology:

• Control group allowed comparisons; large sample size increased generalizability.

Ethics:

• MRI scans used were non-damaging to participants.

Evaluation of Study on Localization

Methodological Evaluation

• Both studies support strict localization and provide insights into specific brain regions related to fear and spatial memory.
• Feinstein et al. raised questions of construct validity due to lack of standardized fear measurements.
• Maguire et al. demonstrated the importance of the hippocampus in spatial navigation with strong methodological rigor.

Validity

• Feinstein et al. had high internal and external validity but variable construct validity.
• Maguire et al. benefited from a large, well-controlled sample size.